This is not an exhaustive look, simply an answer to the OP question of which heroes I really want.
3* I assumed I would eventually get because, well they are 3* and most commonly summoned so didn’t really focus on them.
Nordri was the standout and he is amazing.
Like Grevle too, a mini-mini Heimdall.
4* is where I looked closely because of the possibility to actually summon one (more?) and they could be useful in 5* raiding world so would not be exclusively for tournaments.
MIST:
She was the hero that jumped out at me at the beginning. She was also one of the first 4* to join my team and was immediately made a priority. I have been very pleased with her, a solid 4* (gave her emblems to +18) and no regrets, almost as effective as Proteus for mana slowing at fast mana so a solid addition to mana control stable and complimentary secondary effects.
BRYNHILD:
Agree with poster above saying she is underrated. Her heal and mana boost makes MN effectively average mana and (almost) indestructable. Making buffs undispellable is MUCH more useful than I had expected and she is a source of pleasant surprises, more so once she has some more emblems to digest.
ALMUR:
The Evelyns on my bench cry quietly, Blue tanks quake. That sums it up pretty well.
Gullibursti:
Mini Heimdall, fantastic. Not having experience with him I fear his slow mana in a 5* world but boy do I want to see him in 4* tournaments!
FURA:
Really want her for the healing slow, the max HP reduction will probably be useful too. She looks fragile to me but I’d be happy to have her and find out.
There are others that may be beasts but haven’t immediately sparked desire, this will evolve as heroes prove themselves in game.
5* Heroes
Want pretty much any of them but don’t expect to summon them, have no materials for final ascension and therefore didn’t put huge focus on them.
Heimdall:
Beast. Super heal and small chance of resurrecting dead heroes.
Freya
I’ve changed my mind and want her to join my team. Her minions can be brutal and make a pretty good pseudo heal.
Alfrike
Seems extremely cool and powerful. Wondering how much she would be used against Telluria teams due to mana slow. I see her as the final throw of the dice, if you are ahead when she fires it is just clean-up but she could be the game changer, late to fill her mana and rescues a “lost cause”. Willing to risk it, art is fantastic.
The 5* in Beta look interesting but won’t worry about them until they are released.